Deep-well pump operation variable frequency control method and system

Abstract

The application discloses a deep-well pump operation variable frequency control method and system, and particularly relates to the technical field of liquid level automatic control, which comprises the following steps: system starting and parameter checking; intelligent judgment and switching of operation modes based on water level and water level change rate, including dynamic water supply mode and static maintenance mode; intelligent awakening and protection in the static maintenance mode; sleep frequency self-learning algorithm, which updates sleep frequency and awakening water level according to real-time working conditions; and multi-stage protection logic integrated in the whole process. The application improves the system regulation accuracy, energy-saving effect and self-adaptive ability through the improved variable parameter PID control, static maintenance and intelligent awakening mechanism, and online self-learning ability, and enhances the system reliability and safety through multi-level protection logic.

Description

Technical Field

[0001] This invention relates to the field of automatic liquid level control technology, and more specifically, to a variable frequency control method and system for deep well pump operation. Background Technology

[0002] Currently, in the field of level control for deep well pumps or water supply systems, variable frequency control technology is widely used to achieve energy saving and stable water supply. Common control methods include PID regulation based on a fixed target water level, pump start-stop control based on water level, and variable frequency speed regulation combined with simple threshold judgment. These technologies have achieved automatic level maintenance to a certain extent and reduced energy consumption and mechanical shock caused by frequent pump start-stop.

[0003] However, in practical use, it still has some shortcomings. For example, the fixed parameters of traditional PID control make it difficult to adapt to the dynamic adjustment needs under different water consumption changes, which can easily cause adjustment lag or overshoot oscillation, resulting in water pressure fluctuations. Most solutions do not consider the characteristics of periods without continuous water use, and cannot achieve deep energy saving by intelligently reducing the operating frequency while maintaining a basically stable water level. Existing methods generally lack the ability to learn and adapt to changes in the seepage characteristics of the well body, resulting in long-term solidification of control parameters and a gradual decrease in operating efficiency. The protection logic is often relatively simple or slow to respond. When facing complex operating conditions such as dry running, overcurrent, and communication abnormalities, the reliability and safety of the system still need to be improved. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a variable frequency control method and system for deep well pump operation, which solves the problems mentioned in the background art through the following solutions.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a variable frequency control method for deep well pump operation, comprising:

[0006] S1: Acquire and verify the preset system control parameters, including the maximum safe water level, dry run protection water level, dynamic water supply target water level, wake-up water level, initial sleep frequency, initial start frequency and water level acquisition cycle;

[0007] S2: Start the water pump based on the initial start frequency, and acquire water level data in real time, calculate the water level change rate, until the water level reaches the target water level for dynamic water supply;

[0008] S3: Continuously monitor the water level and the rate of change of the water level, and intelligently determine and switch the operating mode based on the monitoring results:

[0009] When the water level is lower than the target water level for dynamic water supply and the rate of change of water level indicates that there is a demand for water, the dynamic water supply mode is entered. An improved PID control algorithm based on the dynamic adjustment parameter of the pump operating frequency is used to adjust the pump frequency in order to maintain the water level near the target water level for dynamic water supply.

[0010] When the water level is within the static zone defined by the highest safe water level and the wake-up water level, and the water level change rate indicates that there is no continuous water demand, the system enters the static maintenance mode, locks the water pump at the current operating frequency, and allows the water level to fluctuate naturally within the static zone.

[0011] S4: In the static maintenance mode, if the water level is detected to be lower than the wake-up water level, the system is woken up and switched to dynamic water supply mode; if the static maintenance mode lasts for more than a preset duration and the water level remains stable, the sleep frequency self-learning process is triggered to update the initial sleep frequency and the wake-up water level.

[0012] S5: During the execution of S1 to S4, multi-level protection logic is integrated and executed in real time. The protection logic includes at least dry running protection, overcurrent protection, overvoltage / undervoltage protection and communication fault protection, and responds according to preset priorities.

[0013] The technical effects and advantages of this invention are as follows:

[0014] 1. By adopting an improved PID control algorithm that dynamically adjusts parameters in real time based on the pump operating frequency, the problem of lag and oscillation in traditional fixed-parameter PID control when water consumption changes is effectively overcome, and the system achieves rapid and stable tracking of the target water level for dynamic water supply, thereby improving the system response speed and control accuracy.

[0015] 2. A "static maintenance mode" is introduced, which locks the frequency when there is no continuous water demand and allows the water level to fluctuate naturally within a reasonable range. This avoids the frequent fine-tuning required in traditional methods to maintain a fixed water level. Combined with a sleep frequency self-learning algorithm, the system can automatically find the lowest maintenance frequency that matches the current well conditions, thereby achieving deep energy saving.

[0016] 3. Through the sleep frequency self-learning process, the system can calculate and update key parameters online based on actual operating data and well seepage characteristics, so that the control strategy always matches the changing operating conditions, solving the problems of parameter solidification and long-term operating efficiency decline in traditional methods;

[0017] 4. It integrates multi-level protection logic including dry running, overcurrent, overvoltage / undervoltage, and communication failure, and sets a clear priority response mechanism, which can respond and handle various abnormal operating conditions quickly and orderly, improving the system's operational reliability and equipment safety in complex environments.

[0018] 5. During key processes such as mode switching and frequency adjustment, multiple strategies such as anti-shake judgment, smooth transition, and rate limiting were adopted, combined with data filtering preprocessing, to effectively suppress interference such as sensor noise and sudden changes in water usage, ensuring stable water pressure and extending the service life of the equipment. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 This is a schematic diagram of the dynamic water supply mode structure of the present invention.

[0021] Figure 3 This is a schematic diagram of the static maintenance mode structure of the present invention.

[0022] Figure 4 This is a schematic diagram of the multi-level protection logic structure of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] refer to Figures 1-4 The method for frequency conversion control of deep well pump operation shown includes:

[0025] S1: Acquire and verify the preset system control parameters, including the maximum safe water level, dry run protection water level, dynamic water supply target water level, wake-up water level, initial sleep frequency, initial start frequency and water level acquisition cycle;

[0026] S2: Start the water pump based on the initial start frequency, and acquire water level data in real time, calculate the water level change rate, until the water level reaches the target water level for dynamic water supply;

[0027] S3: Continuously monitor the water level and the rate of change of the water level, and intelligently determine and switch the operating mode based on the monitoring results:

[0028] When the water level is lower than the target water level for dynamic water supply and the rate of change of water level indicates that there is a demand for water, the dynamic water supply mode is entered. An improved PID control algorithm based on the dynamic adjustment parameter of the pump operating frequency is used to adjust the pump frequency in order to maintain the water level near the target water level for dynamic water supply.

[0029] When the water level is within the static zone defined by the highest safe water level and the wake-up water level, and the water level change rate indicates that there is no continuous water demand, the system enters the static maintenance mode, locks the water pump at the current operating frequency, and allows the water level to fluctuate naturally within the static zone.

[0030] S4: In the static maintenance mode, if the water level is detected to be lower than the wake-up water level, the system is woken up and switched to dynamic water supply mode; if the static maintenance mode lasts for more than a preset duration and the water level remains stable, the sleep frequency self-learning process is triggered to update the initial sleep frequency and the wake-up water level.

[0031] S5: During the execution of S1 to S4, multi-level protection logic is integrated and executed in real time. The protection logic includes at least dry running protection, overcurrent protection, overvoltage / undervoltage protection and communication fault protection, and responds according to preset priorities.

[0032] S1: System startup and initialization

[0033] S101: Power-on self-test procedure

[0034] After the controller is powered on, it immediately starts a hardware self-test program. The self-test cycle does not exceed 2 seconds, and the specific test contents include:

[0035] Core control module operating status: The processor response speed is detected by the built-in watchdog timer (WDT). If the response delay exceeds 50 milliseconds, the self-test is determined to have failed, and the alarm indicator light is triggered to flash at a frequency of 2Hz.

[0036] Peripheral interface communication verification: sequentially check the connection status of water level sensors, such as ultrasonic / pressure sensors, inverter communication interfaces, relay output ports, and alarm modules. The communication timeout threshold is set to 300 milliseconds. If no valid communication is established, the fault code is recorded and saved to non-volatile memory (EEPROM).

[0037] Power stability detection: Real-time monitoring of input voltage (AC220V±10% or AC380V±10%) and controller internal power supply voltage (DC5V, DC12V). If the voltage fluctuation exceeds ±5%, the startup process will be paused and the self-test will be re-executed after the voltage stabilizes.

[0038] S102: Preset parameter reading and verification

[0039] After the self-test passes, the controller reads the preset parameters from the EEPROM. The parameter reading uses a CRC32 verification mechanism. If the verification fails, the default parameters are automatically called. The definition, value range, default value, and storage address offset of each parameter are as follows:

[0040] Maximum safe water level ( ): Used to prevent overflow, with a value range of 10~50 meters, a default value of 30 meters, and a corresponding storage address offset of 0x0000;

[0041] Dry-to-protection water level ( ): Used to prevent the pump from running dry, with a value range of 2~5 meters, a default value of 3 meters, and a corresponding storage address offset of 0x0004;

[0042] Target water level in dynamic water supply mode ( ): The range of values ​​is between and Between meters, the default value is 25 meters, corresponding to a storage address offset of 0x0008;

[0043] Awakening water level ( ): This serves as the threshold for switching from static mode to dynamic mode, and its value ranges from... Rice and Between meters, the default value is 20 meters, corresponding to a storage address offset of 0x000C;

[0044] Initial sleep frequency ( ): This refers to the pump's minimum operating frequency, ranging from 20 to 30 Hz, with a default value of 22 Hz, corresponding to a storage address offset of 0x0010;

[0045] Initial start-up frequency: The initial output frequency during the pump start-up phase, with a value range of 45~50Hz, a default value of 50Hz, and a corresponding storage address offset of 0x0014;

[0046] Water level sampling frequency: The sampling interval for water level data, with a value range of 50~200 milliseconds, a default value of 100 milliseconds, and a corresponding storage address offset of 0x0018.

[0047] Parameter validation must satisfy the following logical relationships: If the relationship is not satisfied, it will be automatically corrected to the default value and marked as "parameter correction" in the log.

[0048] S103: Pump start control

[0049] After the controller sends a start command to the frequency converter, the pump body is started according to the following procedure:

[0050] After receiving the command, the frequency converter starts in V / F control mode. The initial output frequency is the preset initial start frequency (default 50Hz). During the start-up process, the frequency rise slope is set to 5Hz / s to avoid current surge.

[0051] The controller acquires water level data in real time according to a preset water level acquisition frequency (default 100 milliseconds). And calculate the rate of water level rise. ;

[0052] Startup phase protection logic: If no water level rise is detected within 3 seconds after startup ( If the pump is found to be running dry or the sensor is faulty, a pump stop command will be sent immediately and an alarm will be triggered. If the starting current exceeds 1.5 times the rated current of the pump, the frequency converter will automatically reduce the frequency and limit the current at a rate of 10Hz / s until the current recovers to within 1.2 times the rated current.

[0053] Target water level determination: When detected This state lasts for 3 seconds (anti-shake processing). Once the water level reaches the target value, the controller sends a stable operation command to the frequency converter. After the frequency converter maintains the current frequency for 1 second, the system officially enters the stable monitoring state, waiting for the mode judgment logic to be triggered.

[0054] S104: Initialization complete flag

[0055] After the system enters a stable monitoring state, the controller performs the following initialization and cleanup operations:

[0056] Clear historical fault codes (except for faults that cannot be cleared) and update the system running status register to normal operation;

[0057] The start mode determines the timer, with a timing period consistent with the water level acquisition frequency (100 milliseconds), and then real-time water level monitoring begins. and water level change rate ;

[0058] The alarm indicator light switches from being constantly on upon power-on to flashing during normal operation (frequency 0.5Hz), signaling to the outside world that initialization is complete.

[0059] S2: Intelligent judgment of operating mode

[0060] S201: Monitoring Data Acquisition and Preprocessing

[0061] After the system enters a stable monitoring state, the controller continuously collects real-time water level data output by the water level sensor at a preset water level acquisition frequency (default 100 milliseconds). ( (Sampling time), and simultaneously calculate the rate of change of water level. .

[0062] To avoid misjudgments caused by sensor noise and transient fluctuations, the following preprocessing operations are performed on the collected data:

[0063] Water level data filtering: A 5-point moving average filtering algorithm is used to filter the water level. Effectively suppresses high-frequency noise interference;

[0064] Water level change rate calculation: Based on filtered water level data, the first-order difference method is used for calculation. ,in The sampling period is set (default 100 milliseconds), and the calculation results are limited to a rate of change of less than or equal to 0.5 m / s. If the absolute value of the rate of change is exceeded, it is judged as an abnormal fluctuation, and the rate of change value of the previous moment is temporarily used.

[0065] S202: Dynamic Water Supply Mode Triggering and Control Logic

[0066] Mode trigger condition: When the pre-processed real-time water level meets the requirements When the system determines that there is a continuous water demand or that the water demand is about to increase, it immediately performs a mode switch: if it is currently in "static maintenance mode", the frequency lock state of this mode is immediately interrupted; if it is currently in the initial stable monitoring state, the "dynamic water supply mode" is directly started.

[0067] Improved Variable Parameter PID Control: The core control strategy for the dynamic water supply mode is improved variable parameter PID control, with the goal of quickly responding to water demand and maintaining a stable water level. The specific implementation process is as follows:

[0068] Deviation calculation: Define water level deviation Deviation change ,in This represents the water level deviation at the previous sampling time.

[0069] Variable parameter adjustment mechanism: The proportional coefficient P and integral coefficient I are adjusted according to the current inverter output frequency. Dynamic adjustment is used to avoid issues such as sluggish low-frequency response and high-frequency oscillation. The adjustment formula is as follows:

[0070]

[0071]

[0072] Among them, the PID reference proportional coefficient Scale coefficient adjustment factor PID baseline integral coefficient Integral coefficient adjustment factor , The pump's rated frequency (default 50Hz); when hour, , ;when hour , The intermediate frequency is calculated using linear interpolation;

[0073] PID output calculation: The frequency adjustment increment is calculated using an incremental PID algorithm, as shown in the following formula:

[0074]

[0075] in, This is the frequency adjustment amount for the current sampling period;

[0076] Frequency limiting and smoothing adjustment: The calculated... Output frequency compared to the previous moment Superimpose to obtain the current frequency setpoint And implement dual limiting:

[0077] Range limiting: ensure When the value exceeds the range, the boundary value is used.

[0078] Rate limiting: Limits the rate of change of frequency. To avoid current surges and mechanical vibrations caused by sudden frequency changes;

[0079] Command issued: Set the frequency setpoint after limiting. The signal is sent to the frequency converter via the Modbus protocol, and the frequency converter responds in real time and adjusts the output frequency.

[0080] S203: Static Maintenance Mode Triggering and Control Logic

[0081] Mode Triggering Conditions: When the system meets all of the following conditions, it is determined that there is no continuous water demand, and the system switches from "Dynamic Water Supply Mode" to "Static Maintenance Mode":

[0082] The dynamic water supply mode has been running continuously for at least 5 seconds (anti-shake delay to avoid frequent switching);

[0083] continuous Within the time frame (default 30 seconds), the pretreated water level meets the requirements. ;

[0084] Within the same time period, the rate of change of water level satisfies ,in A minimum threshold value indicates that the water level is basically stable, and .

[0085] Once the trigger condition is met, the controller delays for 1 second to perform mode switching (secondary anti-shake) to ensure accurate judgment.

[0086] Static maintenance core control strategy: The core innovation of the static maintenance mode lies in changing the control objective from "maintaining a fixed water level" to "maintaining the current frequency," and the specific operation is as follows:

[0087] Frequency lockout: The controller records the inverter output frequency at the moment of mode switching. ,in To switch the sampling point and send a "frequency lock command" to the inverter, the frequency setpoint of the inverter is fixed at [value]. Pause PID control output;

[0088] Allowable water level fluctuation range: Set "static zone" as Within this range, the water level is allowed to fluctuate naturally and slowly without frequency adjustment; protection or wake-up logic is triggered only when the water level exceeds this range.

[0089] Operational status monitoring: The controller continues to monitor the water level at a 100-millisecond cycle. and frequency feedback value If the frequency feedback value deviates from the lockout value by more than ±0.5Hz, the controller sends a correction command to the frequency converter to ensure frequency stability; if the water level fluctuation rate suddenly exceeds... If the threshold is still exceeded, the demand status will be reassessed without switching modes.

[0090] Smooth transition during mode switching: When switching from dynamic water supply mode to static maintenance mode, a smooth frequency transition operation is performed: the frequency adjustment rate of the PID output is limited to ≤0.5Hz / s, and the frequency is gradually stabilized to... Then lock is executed to avoid pump vibration and current fluctuation caused by frequency changes, and to ensure that the water pressure change amplitude during the transition is ≤0.02MPa.

[0091] S3: Intelligent wake-up under "Static Maintenance Mode"

[0092] S301: Core Monitoring Mechanism

[0093] After the system enters static maintenance mode, the controller maintains a sampling period of 100 milliseconds and continuously collects filtered water level data. and the actual operating frequency fed back by the frequency converter Simultaneously monitor the following key status parameters:

[0094] Does the water level exceed the "static zone"? ;

[0095] Frequency feedback value and lock value The deviation (allowable deviation range ±0.5Hz);

[0096] Duration of static maintenance mode .

[0097] All monitoring data is stored in the cache in real time. When an abnormal state is triggered, the historical data of the previous 10 seconds can be traced for fault analysis.

[0098] S302: Normal operating condition handling

[0099] When detected At this time, the system maintains a static running state, and the specific operation is as follows:

[0100] Frequency stabilization control: If The controller sends a correction command to the frequency converter, adjusting the output at a rate of 0.2Hz / s until the frequency returns to the locked value;

[0101] Handling slow water level fluctuations: Allow water levels to remain within the static zone. The rate fluctuates naturally, so there is no need to adjust the frequency; only the fluctuation trend is recorded.

[0102] Status update: The system operation log is updated every 5 seconds, recording parameters such as the current water level, frequency, and runtime. The log is saved to EEPROM (maximum of 1000 entries, overwritten cyclically).

[0103] S303: Overflow Protection Triggering and Execution

[0104] When detected When this occurs, the overflow protection logic is immediately triggered, and the execution flow is as follows:

[0105] The controller sends an emergency pump stop command to the frequency converter, which then reduces the frequency to 0Hz at a rate of 5Hz / s to avoid water hammer caused by sudden shutdown.

[0106] Alarm mechanism activated: The alarm indicator flashes at a frequency of 4Hz, the buzzer sounds intermittently (sounds for 1 second, stops for 1 second), and the fault code "E01" (overflow protection) and the water level and frequency data at the time of triggering are recorded.

[0107] Monitoring after pump shutdown: Continue to collect water level data after pump shutdown. If the water level drops to below the warning level within 30 seconds... The alarm status will be automatically cleared, awaiting the next start command; if the water level remains above [a certain level]... Keep the alarm running until manual intervention is required.

[0108] S304: Water Demand Wake-up Logic

[0109] When detected When the current water demand is determined to have recovered, the system switches from static maintenance mode to dynamic water supply mode. The specific steps are as follows:

[0110] Frequency unlock: The controller immediately sends a "frequency unlock command" to unlock. The locked state, while retaining the current frequency as the initial frequency for dynamic mode. ;

[0111] PID fast start: based on current water level deviation Start the improved variable parameter PID control (using the dynamic adjustment mechanism for parameters), with the initial proportional coefficient P and integral coefficient I adjusted according to... calculate;

[0112] Smooth transition: Limit the frequency adjustment rate to ≤1Hz / s to avoid sudden changes in water pressure caused by switching from constant frequency to PID control, and ensure that the water pressure fluctuation amplitude during the transition is ≤0.03MPa;

[0113] Mode confirmation: After switching, monitor continuously for 3 seconds. If the water level deviates... The deviation is gradually reduced, and the switch is deemed successful, with the system officially entering dynamic water supply mode. If the deviation continues to increase, the adjustment range of the PID parameters is increased according to the logic implemented by the improved variable parameter PID control.

[0114] S305: Optimization mechanism after long-term maintenance

[0115] When the static maintenance mode continues to run for a period of time ( (Default 10 minutes), and meets the following conditions When the water level remains essentially unchanged, perform the following optimization operations:

[0116] Triggering sleep frequency self-learning: The controller sends a "learning start command" to the system, initiating the sleep frequency self-learning algorithm and updating the obtained frequency. and ;

[0117] Frequency Update: After learning is complete, the currently locked frequency will be updated. Replace with The activation of the new frequency adopts a smooth transition method, with an adjustment rate of 0.1 Hz / s to avoid frequency abrupt changes;

[0118] Static with update: Update the wake-up water level to The new static strip is adjusted to To ensure it matches the new sleep frequency;

[0119] Run log tag: Record the "sleep frequency update" event in the system log, and save the frequency, water level parameters and learning results before and after the update.

[0120] S306: Emergency Handling of Abnormal Fluctuations

[0121] If the water level change rate is monitored under static maintenance mode However, if the static zone is not exceeded, perform the following emergency procedures:

[0122] Extend the monitoring period: shorten the sampling period to 50 milliseconds and monitor continuously for 5 seconds to determine whether the fluctuation is a transient interference;

[0123] Frequency storage and evaluation: If fluctuations persist for more than 3 seconds, the currently locked frequency is temporarily stored. Start the simplified PID control, i.e., take the proportional coefficient as... 80%, the integral coefficient is taken as 50%, limiting the frequency adjustment range to ;

[0124] Mode return or switch: If the water level fluctuation returns to normal within 5 seconds Stop PID control and resume The water level is locked; if the fluctuations continue to increase and cause the water level to approach... or Execute according to the corresponding wake-up or protection logic.

[0125] S4: Sleep Frequency Self-Learning Algorithm

[0126] S401: Learning Timing Trigger Conditions

[0127] The self-learning of sleep frequency must be triggered in one of the following two scenarios, and a status check must be performed before triggering (ensuring that the system is fault-free and data collection is normal):

[0128] Scenario 1: Normal pump stop trigger in static maintenance mode: When the system reaches a certain water level... When the overflow protection is triggered to stop the pump, the following conditions must be met: the continuous operating time in static maintenance mode before pump stop is ≥3 minutes, and the water level change rate within 1 minute before pump stop is ≥3 minutes. If there are no records of frequency deviation exceeding the limit, the self-learning process will automatically start 3 seconds after the pump stops.

[0129] Scenario 2: Long-term static maintenance trigger: When the static maintenance mode continues to run for a certain period of time And it satisfies: the rate of change of water level within 5 consecutive minutes If the deviation between the frequency feedback value and the lock value is ≤0.3Hz, the frequency lock is paused and the self-learning process is started (during the learning period, the pump is kept running at the current frequency to avoid affecting the stability of the water supply).

[0130] S402: Learning Preparation and Data Collection

[0131] Data acquisition configuration, specifically including:

[0132] Sampling period: During the learning period, the water level sampling period is shortened to 50 milliseconds, while the frequency sampling period remains at 100 milliseconds to ensure data accuracy;

[0133] Data storage: An independent cache area is set up to store water level and frequency data during the learning process, with a cache capacity of ≥1000 records and support for retention after power failure;

[0134] Anomaly removal: The 3σ criterion is used to remove abnormal data, such as instantaneous jump values ​​of sensors, that is, to remove data that is out of range, thus ensuring data validity.

[0135] Pre-calibration parameter: Automatically calibrate pump flow parameters before learning: Correct the pump curve based on the current well water temperature estimated by sensors or ambient temperature, and compensate for the effect of temperature on pump output flow. That is, for every ±5℃ change in temperature, the flow correction coefficient is adjusted by ±1%.

[0136] S403 Core Learning Process

[0137] The average operating frequency calculation includes:

[0138] Scenario 1 (Pump Stop Trigger): Extract frequency feedback data from the last 2 minutes before pump stop. , For a sampling period of 2 minutes × 100 milliseconds, the data from the first 10 seconds and the last 10 seconds are removed to avoid interference during the transition period before and after pump stoppage. The arithmetic mean of the remaining data is then calculated.

[0139] Scenario 2 (Long-term sustained triggering): Extract frequency feedback data from the first 5 minutes of trigger learning, remove data points with a deviation exceeding ±0.2Hz, calculate the weighted average of the remaining data, with recent data weighted at 1.2 and early data weighted at 0.8, to obtain... .

[0140] Seepage time measurement (applicable only to scenario 1): After the pump is stopped, continuously monitor the water level and record the water level from... Naturally descending to time Measurement requirements:

[0141] Initial trigger: When the water level first falls below Start timing at [time] (to avoid accidental triggering due to water level fluctuations);

[0142] End trigger: When the water level first falls below Stop timing when the measurement is complete to ensure that the measurement covers the entire static seepage process.

[0143] Exception handling: If seconds (too fast seepage) or If the seepage is too slow (hours), then the historical data will be used. The mean is used in the calculation.

[0144] Sleep frequency calculation: Based on the principle of energy balance, that is, the pump output flow rate and the well seepage flow rate are balanced, the new sleep frequency is calculated using the following formula.

[0145] Detailed definitions and value rules for each parameter:

[0146] Correction coefficient Used to compensate for factors such as pump efficiency and pipeline losses; default value. It equals 1.15 and can be dynamically adjusted based on actual operating energy consumption. If energy consumption is higher than expected, Increase by 0.05; conversely, decrease by 0.05.

[0147] Target static zone cross-sectional area Based on well diameter estimation, circular wells ,in This is the inner diameter of the well. For non-circular wells, it is calculated based on the equivalent cross-sectional area. It is stored in the system parameters by default and can be manually corrected.

[0148] Pump flow The flow-frequency curve was obtained by fitting the flow rate-frequency curve provided by the pump manufacturer. The fitting formula used was a quadratic polynomial. ,in These are the fitting coefficients, for example, for a certain type of pump. The fitting error is ≤3%;

[0149] Safety limit: calculated Then, take its frequency and the lower limit frequency. The larger value, i.e. This is to avoid insufficient motor heat dissipation due to excessively low frequency.

[0150] Simplified calculations for scenario 2 (none) Measurement)

[0151] In Scenario 2 (learning without stopping the pump), the rate of water level change in the static maintenance mode is monitored in real time. Alternative Calculate the seepage flow rate Then through Reverse push This ensures that the pump output flow rate is balanced with the seepage flow rate.

[0152] S404: Parameter Update and Verification

[0153] Dynamic updates :Will With the present The comparison is performed. If the difference exceeds ±1Hz, the update is performed in three stages, with a 5-second interval between each update and an amplitude of ≤0.5Hz for each update to avoid frequency abrupt changes. If the difference is ≤1Hz, the update is performed directly overwrite. And save it to EEPROM.

[0154] Fine-tuning: based on and The ratio is dynamically adjusted. This allows the wake-up water level to match the sleep frequency: The adjusted condition must meet the following requirements. Otherwise, take the boundary value.

[0155] Learning outcome verification: After updating the parameters, the system verifies the learning outcome in the next static maintenance mode. Validity:

[0156] Verification indicator: Rate of change of water level during static maintenance period No wake-up or protection trigger within 10 minutes of operation;

[0157] Results processing: If the indicators are met, the learning is confirmed to be effective; otherwise, the original parameters are retained and increased during the next learning iteration. Value 0.1, recalculate.

[0158] S405: Learning Failure Handling: When the following situations occur, learning is deemed a failure, and corresponding measures are taken:

[0159] Insufficient data: If the amount of effective sampled data is less than 80% of the total requirement, learning will be terminated and historical data will be used instead. Record the fault code "E08";

[0160] Calculation anomaly: Hz, exceeding the sleep frequency range, then take Hz, and prompts manual inspection of well seepage;

[0161] Consecutive failures: If the learning fails verification after 3 attempts, the current session will be locked. The self-learning function is paused, and an alarm is activated. The alarm indicator light flashes at 2Hz and needs to be manually reset to resume operation.

[0162] S406: Learning Cycle Optimization: The execution interval of the self-learning process should not be less than 24 hours to avoid system fluctuations caused by frequent learning; if the well's seepage characteristics change abruptly, such as If the change exceeds 30%, the interval restriction will be automatically lifted, and a self-learning process will be initiated immediately to ensure that the sleep frequency always adapts to the actual working conditions.

[0163] The S5 protection logic integration

[0164] S501: Dry-start protection (highest priority)

[0165] Triggering condition: Regardless of whether the system is in dynamic water supply mode, static maintenance mode, or startup phase, as long as the filtered real-time water level meets the requirements... This state lasts for 200 milliseconds, with anti-shake processing to prevent accidental triggering of sensor transients and immediately triggering dry running protection.

[0166] The execution process specifically includes:

[0167] Emergency pump stop: The controller sends the highest priority pump stop command to the frequency converter. The frequency converter quickly reduces the frequency to 0Hz at a rate of 10Hz / s and cuts off the power supply circuit of the pump body to prevent the motor from burning out due to idling.

[0168] Alarm mechanism: The alarm indicator flashes rapidly at a frequency of 5Hz, the buzzer sounds continuously, the fault code "E02" (dry run protection) is recorded, and the water level, frequency, and current data at the time of triggering are stored.

[0169] Locked State: After being triggered, the system enters a protection lock state, which prohibits automatic restart. Manual confirmation is required to resolve the fault, such as when well water supply is restored or the sensor is repaired, and the system can be reset via physical buttons or remote commands.

[0170] Recovery conditions: After a manual reset, the system re-executes the power-on self-test and parameter verification. If a fault is detected... If the water level returns to a safe range and the sensor communication is normal, then activation is allowed; otherwise, the system remains locked and continues to alarm.

[0171] S502: Low-frequency limiting protection

[0172] Triggering condition: In dynamic water supply mode, the frequency setpoint calculated by PID. Or the frequency feedback of the frequency converter Minor deviations are permissible.

[0173] The execution process specifically includes:

[0174] Frequency clamping: The controller automatically clamps the frequency setpoint to... It is forbidden to output frequency commands below this value to ensure that the motor speed is not lower than the minimum heat dissipation requirement;

[0175] Status indication: The controller marks "low frequency limiting trigger" in the operation log, and the alarm indicator flashes slowly at a frequency of 0.2Hz. This is not a fault alarm, but only an indication of the status.

[0176] Linked adjustment: If the low-frequency limit continues for more than 5 minutes, the static maintenance mode judgment will be automatically triggered. If the static mode conditions are met, the mode will be switched to avoid inefficient system operation caused by long-term low-frequency PID adjustment.

[0177] Parameter adaptation: The self-learning results are dynamically updated, and the amplitude limit threshold is adjusted synchronously, but it is never lower than the absolute lower limit of 20Hz, ensuring that the motor winding temperature does not exceed 85℃. 85℃ is set based on the motor's heat dissipation characteristics.

[0178] S503: Dynamic Mode Oscillation Suppression

[0179] Oscillation judgment criteria: In dynamic water supply mode, within a 10-second time window (including 100 sampling points), if the inverter output frequency changes direction (upward / downward) ≥8 times, and the frequency change amplitude ≥0.5Hz each time, it is judged as system oscillation, which is manifested as frequent water pressure fluctuations and motor current jitter.

[0180] The execution process specifically includes:

[0181] Frequency Freeze: Immediately enter the "freeze cycle" and set the current frequency to a given value. Fixed, paused PID control, freeze period set to 3 seconds, which can be adjusted via parameters, ranging from 2 to 5 seconds;

[0182] PID parameter reset: During the freeze period, the PID baseline parameter is automatically reduced and adjusted to... Reduce adjustment sensitivity;

[0183] Gradient recovery: After the freeze period ends, the PID control authority is gradually restored at a rate of 0.3Hz / s. The proportional control is enabled first, and the integral control is enabled after 1 second to avoid triggering oscillation again.

[0184] Status Record: Records data such as the number of oscillation triggers, water level deviation at the time of trigger, and frequency range, which are used for subsequent parameter optimization.

[0185] Repeated oscillation handling: If oscillation suppression is triggered 3 times in a row within 1 minute, the system will automatically reduce the frequency adjustment rate limit of the dynamic water supply mode from 2Hz / s to 1Hz / s and continue for 30 minutes. If there is no oscillation during this period, the original limit will be restored. If oscillation is still frequent, the fault code "E03" (PID oscillation fault) will be recorded and an alarm will be triggered, prompting manual optimization of PID parameters or checking the stability of water load.

[0186] S504: Overcurrent Protection

[0187] Triggering condition: Motor operating current is collected via frequency converter. If any of the following conditions are met:

[0188] Operating current Lasting 100 milliseconds, of which This is the pump's rated current;

[0189] Start-up phase current The inrush current exceeded the limit after 50 milliseconds.

[0190] The execution process specifically includes:

[0191] Frequency reduction and current limiting: The controller sends a frequency reduction command to the inverter at a rate of 15Hz / s until the current drops to a minimum. the following;

[0192] Secondary protection: If the frequency is reduced to Afterwards, the current is still greater than or equal to Immediately stop the pump and trigger an alarm, recording the fault code "E04" (overcurrent protection).

[0193] Recovery mechanism: After the overcurrent protection is released, the system will... Restart at the initial frequency and gradually increase the frequency to avoid overcurrent again.

[0194] S505: Overvoltage / Undervoltage Protection

[0195] Triggering condition: Monitor the inverter input voltage (AC220V or AC380V), if the following conditions are met:

[0196] Overvoltage: It lasts for 300 milliseconds, of which This is the rated input voltage;

[0197] Undervoltage: It lasts for 500 milliseconds.

[0198] The execution process specifically includes:

[0199] Voltage anomaly handling: In case of overvoltage, the inverter reduces the output voltage amplitude; in case of undervoltage, the output power is limited to avoid insufficient motor torque.

[0200] Pump stop trigger: If the voltage abnormality lasts for 2 seconds, or the number of abnormal fluctuations is ≥3 times / minute, stop the pump immediately, record the fault code "E05" (overvoltage) or "E06" (undervoltage), and the alarm indicator light will flash at 3Hz;

[0201] Automatic recovery: Voltage restored to After the range stabilizes for 30 seconds, the system will automatically restart and proceed with the startup process.

[0202] S506: Communication Fault Protection

[0203] Triggering condition: Communication interruption between the controller and the frequency converter and water level sensor (RS485 / Modbus protocol timeout). Specific determination:

[0204] Inverter communication: No response after 3 consecutive command transmissions (timeout threshold 300 milliseconds);

[0205] Water level sensor communication: No valid data received for 5 consecutive sampling cycles (timeout threshold 500 milliseconds).

[0206] The execution process specifically includes:

[0207] Safe shutdown: If the problem is a frequency converter communication failure, stop the pump immediately to avoid frequency runaway in the absence of feedback; if the problem is a water level sensor failure, maintain the current mode for 5 seconds, and stop the pump if there is still no data.

[0208] Alarm Log: Record fault code "E07" (communication fault), mark the faulty device (inverter / sensor), and trigger alarm in conjunction with the alarm indicator and buzzer;

[0209] Retry mechanism: After the pump stops, it will attempt to re-establish communication every 10 seconds. If communication is restored, the initialization process will be automatically executed to restart the system. If communication continues to fail, the alarm will be maintained until manual intervention.

[0210] S507: Protection Logic Priority Sequencing

[0211] All protection functions are executed according to the following priorities (from highest to lowest): dry run protection, overcurrent protection, overvoltage / undervoltage protection, communication failure protection, overflow protection, oscillation suppression, and low frequency limiting protection.

[0212] When multiple protection conditions are triggered simultaneously, only the process of the highest priority protection is executed, and the trigger status of other protections is temporarily stored. After the highest priority protection is released, they will be judged and executed in turn.

[0213] This invention also provides a variable frequency control system for deep well pump operation, which includes the following modules:

[0214] Parameter acquisition and verification module: used to perform system startup and initialization, acquire and verify preset system control parameters, including maximum safe water level, dry-run protection water level, dynamic water supply target water level, wake-up water level, initial sleep frequency, initial startup frequency and water level acquisition cycle;

[0215] The water pump is started based on the initial start frequency, and water level data is acquired in real time to calculate the water level change rate until the water level reaches the target water level for dynamic water supply.

[0216] Operating mode judgment and control module: Used to continuously monitor water level and water level change rate, and intelligently judge and switch operating modes based on monitoring results.

[0217] When the water level is lower than the target water level for dynamic water supply and the rate of change indicates that there is a demand for water, the dynamic water supply mode is entered, and the improved PID control algorithm based on the dynamic adjustment parameter of the water pump operating frequency is used to adjust the water pump frequency.

[0218] When the water level is within the static zone defined by the highest safe water level and the wake-up water level, and the rate of change indicates that there is no continuous water demand, the system enters the static maintenance mode and locks the water pump at the current operating frequency.

[0219] Intelligent wake-up and learning trigger module: In static maintenance mode, if the water level is detected to be lower than the wake-up water level, the system will be woken up and a switch to dynamic water supply mode will be triggered; if the static maintenance mode lasts for more than a preset duration and the water level remains stable, the sleep frequency self-learning process will be triggered.

[0220] Sleep frequency self-learning module: When the trigger conditions are met, it collects the water pump operating frequency and water level data, calculates the sleep frequency adapted to the current working conditions based on the energy balance principle, and updates the sleep frequency and wake-up water level parameters in the system.

[0221] Multi-level protection logic execution module: used to execute multi-level protection logic in real time during the entire system operation, including at least dry run protection, overcurrent protection, overvoltage / undervoltage protection and communication fault protection, and respond to various abnormal states according to preset priorities.

[0222] Secondly: The accompanying drawings of the embodiments disclosed in this invention only involve the structures involved in the embodiments disclosed in this invention. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other.

[0223] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A variable frequency control method for deep well pump operation, characterized in that, include: S1: Acquire and verify the preset system control parameters, including the maximum safe water level, dry run protection water level, dynamic water supply target water level, wake-up water level, initial sleep frequency, initial start frequency and water level acquisition cycle; S2: Start the water pump based on the initial start frequency, and acquire water level data in real time, calculate the water level change rate, until the water level reaches the target water level for dynamic water supply; S3: Continuously monitor the water level and the rate of change of the water level, and intelligently determine and switch the operating mode based on the monitoring results: When the water level is lower than the target water level for dynamic water supply and the rate of change of water level indicates that there is a demand for water, the dynamic water supply mode is entered. An improved PID control algorithm based on the dynamic adjustment parameter of the pump operating frequency is used to adjust the pump frequency in order to maintain the water level near the target water level for dynamic water supply. The adjustment of the water pump frequency includes: dynamically adjusting the values ​​of the proportional control parameter and the integral control parameter according to the current operating frequency of the water pump, wherein the higher the operating frequency, the greater the values ​​of the proportional control parameter and the integral control parameter; calculating the required frequency adjustment amount using an incremental PID algorithm based on the dynamically adjusted proportional control parameter and integral control parameter; and applying dual constraints to the calculated frequency setpoint: first, limiting it to a preset maximum and minimum frequency range; second, limiting its variation amplitude per unit time to avoid sudden frequency changes. When the water level is within the static zone defined by the highest safe water level and the wake-up water level, and the water level change rate indicates that there is no continuous water demand, the system enters the static maintenance mode, locks the water pump at the current operating frequency, and allows the water level to fluctuate naturally within the static zone. When the system simultaneously meets the following conditions, it is determined that there is no continuous water demand, and the system switches from the dynamic water supply mode to the static maintenance mode: the dynamic water supply mode has been running for at least a preset anti-shake delay time; the pre-processed water level is not lower than the dynamic water supply target water level during a continuous first time period; and the absolute value of the water level change rate does not exceed a preset threshold during the same time period. S4: In the static maintenance mode, if the water level is detected to be lower than the wake-up water level, the system is woken up and switched to dynamic water supply mode; if the static maintenance mode lasts for more than a preset duration and the water level remains stable, the sleep frequency self-learning process is triggered to update the initial sleep frequency and the wake-up water level. The sleep frequency self-learning process includes: when a preset trigger condition is met, collecting the operating frequency and corresponding water level data of the water pump under specific operating conditions; based on the operating frequency and water level data, calculating a sleep frequency that matches the current well seepage flow rate according to the energy balance principle; updating the initial sleep frequency parameters stored in the system according to the calculated sleep frequency, and synchronously adjusting the wake-up water level so that the updated wake-up water level is adapted to the new sleep frequency; The calculation of the sleep frequency matching the current well seepage flow rate based on the energy balance principle includes: in the static maintenance mode without stopping the pump learning scenario, calculating the well seepage flow rate based on the water level change rate and the target static zone cross-sectional area under the static maintenance mode, and back-deriving the sleep frequency that satisfies the balance between the pump output flow rate and the well seepage flow rate based on the pump flow rate-frequency curve; in the pump stop trigger learning scenario, calculating a new sleep frequency based on the energy balance principle, i.e., the balance between the pump output flow rate and the well seepage flow rate; after calculating the new sleep frequency, taking the larger value between the new sleep frequency and the lower limit frequency; S5: During the execution of S1 to S4, multi-level protection logic is integrated and executed in real time. The protection logic includes at least dry running protection, overcurrent protection, overvoltage / undervoltage protection and communication fault protection, and responds according to preset priorities.

2. The variable frequency control method for deep well pump operation according to claim 1, characterized in that, The dry-run protection includes: When the real-time water level is lower than the dry run protection water level, and this state continues for a preset anti-shake time, the dry run protection is immediately triggered. Upon triggering, the controller sends a highest priority pump stop command to the frequency converter, controlling the water pump to quickly reduce its frequency to a stop at a preset rate; At the same time, the system enters a protection lockout state, triggers an audible and visual alarm, records fault information, and prohibits automatic restart before manual reset.

3. The variable frequency control method for deep well pump operation according to claim 1, characterized in that, The overcurrent protection includes: The system monitors the operating current of the water pump motor in real time. If the operating current exceeds a first preset multiple of the pump's rated current and remains above a first time threshold, overcurrent protection is triggered. After triggering, the controller sends a frequency reduction command to the frequency converter to reduce the water pump's operating frequency at a preset frequency reduction rate until the operating current returns to a safe range. If the operating current still exceeds a second preset multiple after the frequency is reduced to the minimum allowable frequency, an emergency pump stop is executed and an alarm is triggered.

4. The variable frequency control method for deep well pump operation according to claim 1, characterized in that, The overvoltage / undervoltage protection includes: The inverter's input voltage is monitored in real time. If the input voltage continuously exceeds a first preset proportion of the rated voltage and reaches an overvoltage judgment time, overvoltage protection is triggered. If the input voltage continuously falls below a second preset proportion of the rated voltage and reaches an undervoltage judgment time, undervoltage protection is triggered. After the corresponding protection is triggered, the controller performs the corresponding output reduction or power limiting operation. If the abnormal voltage condition continues to exceed a total duration threshold, the water pump is controlled to stop and an alarm is triggered.

5. The variable frequency control method for deep well pump operation according to claim 1, characterized in that, The communication fault protection includes: The system monitors the communication status between the controller and the frequency converter, as well as between the controller and the water level sensor, in real time. If there is no response to the communication with the frequency converter for several consecutive times, or if no valid data is received from the communication with the water level sensor for several consecutive sampling cycles, it is determined to be a communication fault. After the communication fault protection is triggered, a safe shutdown operation is performed according to the faulty equipment type, and the corresponding fault alarm information is recorded. After the shutdown, the controller attempts to re-establish communication according to a preset cycle. If the communication is restored, the system initialization process is automatically executed.

6. A variable frequency control system for deep well pump operation, said system being used to implement the variable frequency control method for deep well pump operation as described in any one of claims 1-5, characterized in that, include: Parameter acquisition and verification module: used to perform system startup and initialization, acquire and verify preset system control parameters, including maximum safe water level, dry-run protection water level, dynamic water supply target water level, wake-up water level, initial sleep frequency, initial startup frequency and water level acquisition cycle; The water pump is started based on the initial start frequency, and water level data is acquired in real time to calculate the water level change rate until the water level reaches the target water level for dynamic water supply. Operating mode judgment and control module: Used to continuously monitor water level and water level change rate, and intelligently judge and switch operating modes based on monitoring results. When the water level is lower than the target water level for dynamic water supply and the rate of change indicates that there is a demand for water, the dynamic water supply mode is entered, and the improved PID control algorithm based on the dynamic adjustment parameter of the water pump operating frequency is used to adjust the water pump frequency. When the water level is within the static zone defined by the highest safe water level and the wake-up water level, and the rate of change indicates that there is no continuous water demand, the system enters the static maintenance mode and locks the water pump at the current operating frequency. Intelligent wake-up and learning trigger module: In static maintenance mode, if the water level is detected to be lower than the wake-up water level, the system will be woken up and a switch to dynamic water supply mode will be triggered; if the static maintenance mode lasts for more than a preset duration and the water level remains stable, the sleep frequency self-learning process will be triggered. Sleep frequency self-learning module: When the trigger conditions are met, it collects the water pump operating frequency and water level data, calculates the sleep frequency adapted to the current working conditions based on the energy balance principle, and updates the sleep frequency and wake-up water level parameters in the system. Multi-level protection logic execution module: used to execute multi-level protection logic in real time during the entire system operation, including at least dry run protection, overcurrent protection, overvoltage / undervoltage protection and communication fault protection, and respond to various abnormal states according to preset priorities.

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